The present invention relates to a woven substrate which is formed into a three dimensional article by thermoforming or other means suitable for purpose.
Fiber reinforced composite structures enjoy the benefit of being lightweight while providing mechanical advantages such as strength. However, in many applications, molded plastic, wood or metal structures are preferred due to the cost involved, since they are relatively easy to fabricate. Often times however, articles, such as package or storing crates, are prone to damage due to the rough handling involved or are limited in their stacking ability due to weight and strength considerations. While fiber reinforced composite structures would be more desirable, the expense involved in making a somewhat complex three dimensional (3D) structure is a consideration.
This is because composite structures start off typically with a woven flat substrate of fibers. The substrate then has to be shaped into the form of the article which is then coated with a resin and thermoformed or cured in the desired shape. This may be readily done for relatively flat or smooth surfaces. However, for angled surfaces such as at the junction of the sides, corners and bottoms of a box or crate, cutting or darting is required. This is somewhat labor intensive and adds to the cost of manufacture. For things typically considered to be inexpensive, for example a packaging crate, the added expense may outweigh the benefits of it being reinforced.
While woven 3D structures may be woven by specialized machines, the expense involved is considerable and rarely is it desirable to have a weaving machine dedicated to creating a simple structure.
Accordingly, while woven fiber reinforced articles are desirable in many applications to replace comparable plastic, wood or metal structures, there exists a need to reduce the cost involved in the method of their manufacture. By doing so it may also allow for their relative mass production and wide spread application.
It is therefore a principal object of the invention to minimize or eliminate the need to cut and dart woven reinforcing fabrics for 3D structures.
It is a further object as part of this to simplify the manufacture of such structures and reduce the labor requirement.
A yet further object of the invention is to avoid the need for special weaving equipment to create 3D structures.
A still further object is to provide for a method of creating a woven reinforcing fabric which may be readily adapted to create a wide variety of different 3D structures.
These and other objects and advantages will be apparent from the present invention. The present invention is directed toward providing a specially designed fabric suitable as the reinforcement for a 3D composite structure. The fiber reinforcement is one that may be woven on conventional weaving machinery. It starts off as a woven 2D structure that is then formed into a 3D structure, particularly one having deep draws. To provide for this, the reinforcing fabric is woven in a manner that, in portions of the weave, the warp and weft or fill fibers are laid on each other and do not interlock. In this portion the fibers can move independently and slide past one another when the fabric is drawn or folded into shape. If the portion is a rectangular or square shape, it can be collapsed in such a manner that both the warp and weft fibers fold upon themselves and each other to align in an unidirectional manner which creates a corner which acts as a compression column in the final structure.